TableViewController cells not populating with data - ios

Question

Alright, I know I'm going to annoy someone here with my n00b-ness, so consider this a fair warning. I'm fresh-as-a-fish to Obj-C, and so what may be obvious to you most likely won't to me.
I've been following this tutorial on TableViewControllers, and I can't for the life of me get the cell titles to appear. I have cut and retailored every line of code on the site, and debugged a SIGABRT error, yet even now the data does not appear.
Here is the contents of the MasterViewController.h and /.m files, respectively:
The header file:
#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
#import <UIKit/UIKit.h>
#class DetailViewController;
#interface MasterViewController : UITableViewController <NSFetchedResultsControllerDelegate, UITableViewDelegate, UITableViewDataSource>
#property (strong, nonatomic) DetailViewController *detailViewController;
// Create property "equations" as an instance of NSArray:
#property (strong, nonatomic) NSMutableArray *equations;
#property (strong, nonatomic) NSFetchedResultsController *fetchedResultsController;
#property (strong, nonatomic) NSManagedObjectContext *managedObjectContext;
#end
The implementation file:
#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
#import "MasterViewController.h"
#import "DetailViewController.h"
#interface MasterViewController ()
- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath;
#end
#implementation MasterViewController
// Synthesize NSArray instance for equation storage:
#synthesize equations = _equations;
// Segue linking as per DetailViewController.h/.m:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"showDetail"]) {
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
DetailViewController *destViewController = segue.destinationViewController;
destViewController.equationName = [_equations objectAtIndex:indexPath.row];
}
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.navigationItem.leftBarButtonItem = self.editButtonItem;
UIBarButtonItem *addButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:#selector(insertNewObject:)];
self.navigationItem.rightBarButtonItem = addButton;
self.detailViewController = (DetailViewController *)[[self.splitViewController.viewControllers lastObject] topViewController];
self.title = #"Equations";
if (!_equations)
{
_equations = [[NSMutableArray alloc] initWithObjects:
// Atomic structure equations:
#"Energy-Frequency Relation",
#"Energy-Frequency-Wavelength Relation",
#"Energy-Quantum Number Relation",
#"Momentum-Mass-Frequency",
#"Speed of Light Definition",
// Equilibrium equations:
#"Equilibrium Acid Constant",
#"Equilibrium Base Constant",
#"Water Equilibrium Constant",
#"pH Calculation",
#"pH-Acid Constant Relation",
#"pOH-Base Constant Relation",
#"pKa Derivation",
#"pKb Derivation",
#"pOH Calculation",
#"Gas-pressure Equlibrium",
// Gas/solution chemistry equations:
#"Ideal-Gas Law",
#"Partial-pressure equation",
#"Total pressure (3 partials)",
#"mol-Molarity Calculation",
#"Kelvin-Celsius Relation",
#"Fahrenheit-Celsius Relation",
#"Density Calculation",
#"Kinetic Energy per Molecule",
#"Kinetic Energy per Mol",
#"Molarity Equation",
#"Molality Equation",
#"Absorbance Equation",
#"Freezing Point Depression",
#"Boiling Point Elevation"
// Redox Equations:
#"Electrical current definition",
#"Equilibrium vs. Reduction Potential",
// Thermochemical relations:
#"Change in Free Energy",
#"Molar Heat Capacity",
#"Frequency to Rate Factor",
nil];
}
}
#pragma mark - Table View
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return call from NSArray *equations as to the count of elements in the table view:
return [_equations count];
}
- (UITableViewCell *)tableView: (UITableView *)tableView cellForRowAtIndexPath: (NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell"];
UILabel *lblName = (UILabel *)[cell viewWithTag:100];
[lblName setText:[_equations objectAtIndex:[indexPath row]]];
return cell;
}
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
// Return NO if you do not want the specified item to be editable.
return NO;
}
I spared y'all all 250 lines of code, cutting out only that seem to pertain to the view controller itself. Something tells me I'm simply leaving out a necessary line of code for connection, however my complete introductory status to the language as well as the lack of a debugger error doesn't trip me to it. Any ideas? Any help (nitpicking excluded) is more than appreciated and welcomed.

Answer 1

#"Cell"that could be a couple of things you can check here.
in your cellFoRowAtIndexPaht Method
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell"];
//add this
if (cell == nil)
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"Cell"] autorelease];
double check if your table data source and table delegate is connected correctly to your table view. i think when you create uitableviewcontroller from storyboard, it should connected for you automatically, but it won't harm to double check.

Answer 2

I was able to reproduce your issue as follows:
Your current tableView:cellForRowAtIndexPath: implementation requires that the cell have a UILabel subview with a tag of 100.
UILabel *lblName = (UILabel *)[cell viewWithTag:100];
The label in the cell needs to be configured with this tag...
If you are using the "Basic" cell type in Interface Builder you have two options:
Option 1
You must select the title label and set it's tag to 100.
Option 2
Change the method to directly access the text label.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell"];
[cell.textLabel setText:_equations[indexPath.row]];
return cell;
}
You can also use an approach similar to (if not identical to) Option 2 for custom cell types where you have provided your own label.